Badges for Adult Only category

I think what I’m asking is something like this: We’re using the “secure non public category” feature for our AO category, but there’s nothing truly secure, secret, or private about it. We just want people to opt-in to see mature content. We have a policy where everybody who says that they’re an adult and that they want access to the AO category gets access.

Is there another, better way to implement our AO category? Ideally these posts would indeed be public but filtered out, or something…?